Photocell control circuit for motor-operated toy

ABSTRACT

An electric circuit responsive to a difference in the intensity of radiation, such as light, between two positions, for controlling the operative state of a load. The circuit includes a pair of series-connected photocells which provide the input to a solid state amplifier which includes an output stage acting as a switch. In one embodiment, the output switching stage is in series circuit with a source of power and a motor mounted on a toy, such as a vehicle, so that the motor is actuated when the switching stage is conducting. Feedback means are provided in circuit with the amplifier and the switching stage so that the operative state of the load, such as the operation of the toy motor, is maintained after the difference in radiation intensity between the first photocell and the second photocell has ceased. In another embodiment, a pair of amplifier paths are provided to control both the actuation and deactuation of the load. The circuit may be provided as an attachment for a toy model wherein an insulating element capable of being bypassed by the output switching stage of the amplifier is in circuit with the power supply to the motor of the toy. A modification to the circuit is disclosed wherein the difference in radiation intensity between the photocells controls the movement of the toy in its forward, reverse, left, or right directions without the need for using reversing relays.

United States Patent 1 3,621,356

[72] inventor Kwan Chi 0n Primary Examiner-Gris L. Rader 1800 Grant St.,Berkeley, Calif. 94703 Assistant Examiner-Robert .1. Hickey [211 App].No. 857,912 Attorney-Lane, Aitken, Dunner & Ziems [22] Filed Sept. 15,1969 [45] Patented Nov. 16, 1971 ABSTRACT: An electric circuitresponsive to a difference In the intensity of radiation, such as light,between two positions, for controlling the operative state of a load.The circuit in- [54] PHOTOCELL CONTROL CIRCUIT FOR MOTOR cludes a pairof series-connected photocells which provide the OPERATED TOY input to asolid state amplifier which includes an output stage 14 CW4 Drawingacting as a switch. in one embodiment, the output switching stage is inseries circuit with a source of power and a motor [52] US. Cl. 318/480,mounted on a my. such as a vehicle so that the motor is 46/244 250/2101318/257 ated when the switching stage is conducting. Feedback means1111- P are provided in circuit with the amplifier and the switching 139/ 12 stage so that the operative state of the load, such as the opera-[50] Field of Search 318/480, ion f the my motor is maintained fl hedifi g e i 139, l7, 257; 317/124, 127; 307/1 17; radiation intensitybetween the first photocell and the second 330/59; 250/208 210; 46/244 Cphotocell has ceased. In another embodiment. a pair of amplifier pathsare provided to control both the actuation and deac- [56] Ranch CMtuation of the load. The circuit may be provided as an at- UNITED STATESPATENTS tachment for a toy model wherein an insulating element capa-3,293,522 12/1966 Lewis 318/257 X ble of being bypassed by the outputswitching stage of the am- 2,921,408 1/1960 Leblic 318/480 X plifier isin circuit with the power supply to the motor of the 3,130,803 4/1964Wiggins... 46/244 C X toy. A modification to the circuit is disclosedwherein the dif- 3,199,005 8/1965 Ashworth 318/16 ference in radiationintensity between the photocells controls 3,218,461 11/1965 Saunders eta1. 250/210 X the movement of the toy in its forward, reverse, left. orright 3,502,883 3/1970 Archer 250/209 X directions without the need forusing reversing relays.

PATENTEBunv 16mm 3.621.356

sum 1 0F 2 FIG. I.

INVENTOR CHI ON KWAN ()RNEYS PATENTEDunv 16 IS?! 3.621.356

sum 2 or 2 FIG. 2.

INVENTOR CHI-ON KWAN BACKGROUND OF THE INVENTION This invention relatesto a control circuit responsive to a difference in radiation intensitybetween two positions. More particularly, this invention relates to acontrol circuit for controlling the operative state of a motor incircuit with a source of power. Still more particularly, this inventionrelates to a control circuit which is capable of being applied to a toymodel having a motor in series with a source of direct current potentialfor controlling the operation of the toy as a function of a differencein radiation intensity between a pair of photocells in the circuit.

It is often a desire in the electronic arts to control the operative'state of a load by using a source of radiation, for example, light. Suchcontrol permits the controlling parameter to be located at a pointremote from the load without requiring intervening circuit connections.Thus, the prior art has produced a number of circuits which utilizephotoresponsive circuit elements, including solid state devices, toswitch a load from one operative state to another.

In such control circuits, it is a continuing problem to provide circuitmeans which maintain the switched state of the load without requiringthat a source of controlling light be continuously provided. MOreover,in certain instances, it has been necessary to provide a plurality ofswitching circuits to control both the actuation and deactuation of theload, such as a motor, by a source of light.

A known circuit utilizes a photo responsive relay circuit which includesa pair of photocells connected so that the circuit responds to adifi'erence in light intensity between the cells. As is well known, theresistance of a photocell is generally a function of the light intensityincident to the cell. In that particular arrangement, the midpoint of apair of photocells is connected to the base of a transistor whichactivates a trigger circuit which in turn controls a relay. The outputfrom a multivibrator in that system, connected in circuit with theamplifier, actuates a relay. The length of time that the relay remainsclosed depends upon the size of a capacitor in circuit with the relay.

Control of the movement of toys from a location remote from the toy andwithout need for intervening circuit connections also continues to be aproblem, for which the use of a photocell has provided some relief.Thus, arrangements are known for controlling the operation of toys by asource of light remote from the toy. Such solutions have not beenwithout difficulty, however, caused, for example, by the problem ofavoiding the undesirable operation of the toy by a change in the ambientlight level. In some instances, reflectors and lightshielding structureshave been used to avoid this difficulty. Moreover, it has generally beenquite difiicult to control the operation of a toy under both dark andlight ambient conditions. Thus, toys designed to operate in outdoorsunlight have not operated completely satisfactorily in the somewhatdarker indoor environment and vice versa.

The movement of the toy illustrates the need in the art to provide meansfor continuing the operation of the motor after the incident light hasbeen removed. It is annoying to the operator of the toy when he mustfollow the toy about, continuously shining light upon the photocell tocause the operation of the motor. Thus, it is also an aim in the art toprovide means to cause the continued operation of the toy after thesource of light has been removed.

Thus, it is an object of this invention to provide a circuit forcontrolling the operation of the load in a predetermined manner which isresponsive to a difference in the intensity of radiation, for examplelight, incident upon two control positions.

It is a further object of this invention to provide a circuit responsiveto a differential level of radiation which includes means for continuingthe switched state of the load after the controlling radiation hasceased.

It is a further object of this invention to provide a lightresponsivecircuit for controlling the operation of a toy.

It is still a further object of this invention to provide alightresponsive circuit which controls both the actuation anddeactuation of the motor on a toy, such as a vehicle.

It is still a further object of this invention to provide aphotoresponsive electrical circuit which may be applied to knownmotor-operated toy vehicles so that such toys may be remote controlled.

SUMMARY OF THE INVENTION A circuit which achieves the objects of thisinvention and overcomes the above-mentioned problems in the prior artcomprises a pair of radiation-responsive elements, such as photoresponsive solid state devices, for example, photocells, connected incircuit to respond to a difference in incident radiation intensitybetween the two devices. Amplifier means are in circuit with thephotocells for responding to the change in signal level across either ofthe elements. Switch means, such as a transistor capable of beingswitched from its nonconductive state to a saturation state is incircuit with the amplifier for controlling the operative state of aload, for example, a motor in series with a source of power, such as maybe found in a toy vehicle. It is a feature of the invention that themotor will be controlled by the photoresponsive devices by apredetermined sequence of illuminating or shadowing the light incidenton those devices.

In a preferred embodiment, the amplifiers include directcoupledtransistors having an output which is connected to a transistor switch.Positive feedback is provided from the output of the transistor switchto the input of one of the transistor amplifier stages to maintain theconductive state of switch and thus the operative state of the loadafter the dilTerence in light intensity on the photocells has ceased.Second amplifier means, comprising at least a pair of direct-coupledtransistor stages, are also connected to the photocells for changing theoperative state of the load in a direction opposite to that previouslydiscussed and in response to a predetermined sequence of illuminating orshadowing the light incident on the photoresponsive devices.

Means are also disclosed for utilizing illumination to control both thedirection and the steering of the toy vehicle without requiringreversing relays. Output means are provided for the circuit whichinclude an element for disconnecting the motor from the source of powerso that the operation of the motor is controlled by the photoresponsivecircuit. In this manner, the circuit may be readily added to toys havinga source of power and a motor to provide them with a remote-controlcapability.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a circuit diagram illustrating one form of the invention forcontrolling the operative state of a motor in series with a source ofpower;

FIG. 2 is a modified circuit according to the invention for controllingthe activation and deactivation of the load in circuit with a source ofpower supply;

FIG. 3 is an illustration of the invention as applied to a toy model,such as a toy truck; and

FIG. 4 is a circuit diagram showing a further modification of thecircuit according to the invention.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, input circuit means aredesignated generally at 10 and comprise a first element, such as aphotoresponsive device, for example, a photocell 11 connected to asimilar photoresponsive device, for example, photocell l2. Photocells ll and 12 are connected in series across a source of electrical power,for example, a direct-current battery 13 located on a toy model.Positive bias is supplied to the circuit on lead 14 and negative bias issupplied to the circuit on lead 15.

First amplifier means are designated generally at 17 and comprise afirst transistor T1 including a base 19, emitter 20 and collector 21coupled by way of lead 22 to the base 23 of transistor T2. Transistor T1is biased by the connection of its emitter 20 to the junction ofresistors R1 and R2 connected between leads 14 and 15.

Transistor T2 also includes an emitter 24 connected to bias lead 14 anda collector 25. Switching amplifier means designated generally at 27include a transistor T3 having a base 28 coupled to the collector 25 oftransistor T2. Emitter 29 of transistor T3 is connected to the negativebias lead while collector 30 of transistor T3 is in circuit with theload, for example, motor 33, by way of lead 31.

Positive feedback is provided from the collector 30 of transistor T3 tothe base 23 of transistor T2 through resistor R3.

Photocells 11 and 12 respond to a variation in the radiation intensitybetween the cells to control the operation of motor 33. While the sourceof-radiation will generally be discussed as a source of light, it may beunderstood that other sources of radiation, visible or invisible, mayalso be used to actuate an appropriately responsive element.

In operation, photocells 11 and 12 operate to provide a responsecorresponding to the presence of illumination on one cell, the presenceof a shadow on the other cell or a combination of lighting or shadowingwhich will produce a difference in the light intensity applied to therespective cells. That difference in radiation intensity between thecells will generally be referred to as the difference in radiationbetween the two positions, or upon the two cells.

When photocell 11 receives light, its resistance decreases. A decreasein the resistance of photocell 11 causes an increase in the magnitude ofthe positive voltage applied to the base 19 of transistor T] from lead14. Thus, the base current applied to transistor T1 increases. Anincrease in current to the base of T1 causes T1 either to conduct orincreases its conductivity, depending on its initial state. As T1conducts, T2 either conducts or increases its conductivity which furthercauses transistor T3 to conduct toward saturation. As transistor T3increases conduction, the current in collector 30 increases and providespositive feedback through resistor R3 to the base 23 of transistor T2 tofurther assist driving transistor T3 quickly into saturation.

A series loop comprises battery 13, motor 33, lead 31, transistor T3,emitter 29 and a portion of the bias lead 15. Thus, the state ofconduction of transistor T3 acts as a switch for the operation of themotor 33. When the transistor T3 is off, an open circuit exists and themotor is deactuated. When transistor T3 is driven to saturation, thecircuit becomes closed to actuate the motor 33.

The above operation of the circuit will likewise operate, ashereinbefore discussed, by the presence of a shadow on photocell 12which further causes an increase in its resistance, thus increasing theapplied voltage to the base of transistor T1, or by a combination oflight applied to photocell I1 and a shadow applied to photocell 12.Moreover, application of light of greater intensity to photocell 11 thanthe intensity of light applied to photocell 12 will cause the circuit tooperate as described.

Positive feedback through resistor R3 causes the circuit to possess amemory capability since transistor T3 will remain in its saturated stateby action of the positive feedback after the light differential betweenphotocells l1 and 12 has terminated. Thus, the action of the positivefeedback causes the motor 33 to be maintained in its running condition.

Light applied to photocell 12 or a shadow applied to photocell 11 willstop the motor. Each of these conditions causes a more negativepotential to be applied to the base os transistor T1 decreasing the basecurrent to transistor T1 and decreasing its conduction. Thereforetransistor T2 conducts less causing transistor T3 to conduct less untiltransistor T3 is driven to its nonconductive state. The action of thepositive feedback also assists in driving transistor to its "off" state.

In FIG. 2, circuit elements and connections which correspond to thosedescribed in FIG. 1 are identified with like reference numerals so thatdetailed discussion need not be repeated.

Second amplifier means designated generally at 40 comprise a pair ofdirect-coupled transistors T4 and T5. Transistor T4 comprises a base 41,an emitter 42 and a collector 43. Base 41 is connected by way of circuitlead 45 to the common junction between photocells 11 and 12. Base 19 oftransistor T1 is also connected through lead 45 to the junction betweenphotocells 11 and 12. Transistor T5 comprises a base 47, an emitter 48and a collector 49 which is connected to the base 28 of transistor T3 byway of lead 51. Transistors T1 and T4 are biased by the seriesconnection of resistors R4, R5 and R6 between bias leads 14 and 15.

The action of amplifier 17 and transistor T3 has been described for thecondition in which the photocell 11 is lighted, or photocell 12 isshadowed. Under those same conditions, he transistors T4 and T5 will berendered nonconductive by the increase in potential applied to the baseof transistor T4. If transistors T4 and T5 are conductive when photocell11 is illuminated, lead 45 becomes more positive and when applied to thebase 41 of the transistor T4 would cause T4 to become nonconductive.Thus, current flow to the base 47 of transistor T5 is likewise reducedto render transistor T5 nonconductive.

The circuit of FIG. 2 also permits the operative state of motor 33 to becontrolled in a direction opposite to that previously discussed. Thus,to turn motor 33 off after it is running, and held in that operativestate by the positive feedback action through resistor R3, a difi'erencein the radiation level on photocells 1 1 and 12in a direction oppositeto that previously discussed achieves the desired action as previouslydiscussed. Thus, if photocell 12 is illuminated, its resistance willdecrease and the potential at the common junction between photocells l land 12, and hence, to lead 45 becomes more negative. The application ofa more negative voltage to the base 19 of transistor T1 turns transistorT1 off. Simultaneously, application of a more negative voltage to thebase 41 of transistor T4 tends to cause transistor T4 to conduct.

An increased conduction of transistor T4 increases the current atcollector 43 of transistor T4 which, when applied to the base 47 oftransistor T5, turns transistor T5 on. An increase in the collectorcurrent from the increased conduction of transistor T5 in the lead 51 isapplied to the base 28 of transistor T3 to open the transistor switch T3in a manner op posite to that previously discussed.

Thus, when transistor T3 is opened, the series circuit involving motor33 and power source 13 is rendered nonconductive.

One of the capabilities of the circuit is its ready applicability, whenpackaged in convenient for, to cause a batteryoperated, motorized toyvehicle to be capable of remote control. To this end, an element 60,comprising conductive plate 61, insulating plate 62, and conductiveplate 63 in a sandwichlike arrangement is inserted between the motor byway of lead 64 and a source of power 13. Conductive plate 63 isconnected by way of lead 65 to the emitter of transistor switch T3 whileconductive plate 61 is connected by way of lead 31 to collector 30 oftransistor switch T3.

Thus, when transistor T3 is opened, insulating plate 62 prevents theapplication of power in a complete circuit from source 13 to motor 33.When the switch T3 is closed, insulating plate 62 is bypassed by theconductivity of the transistor T3 to close the circuit and thus actuatemotor 33.

FIG. 3 illustrates the ready application of the circuit according toFIGS. 1, 2 or 4 to a toy vehicle, such as a truck designated generallyat 70. In this embodiment, photocells 11 and 12 are shown mounted on thecab 71 of the toy vehicle. Element 72 illustratively shows the circuitelements of either FIGS. 1, 2 or 4 in operative connection withbatteries 74 and 75 which are equivalent to the power source 13previously discussed. Motor 76 is shown diagrammatically in phantomoutline for driving the rear wheels of the truck in accordance with theconditions of illumination previously discussed. It may be understoodthat the circuit may be packaged in convenient form, such asencapsulated in epoxy as at 72 and applied to a convenient outsidesurface of the toy vehicle to expose photocells 11 and 12 toillumination in accordance with the teachings of this invention. By theinsertion of element 60, as previously described, between the batteries74 and 75 in a series circuit with motor 76 via lead 77, the operationof the truck is rendered responsive to the selected level ofillumination on the photocells.

MOdification of the circuit as shown in FIG. 4 will permit the controlof the vehicle in its forward or backward direction, as well as its leftor right direction, depending upon the connection of the motor to thewheels of the vehicle. If the motor is connected to the wheels of thevehicle to provide a driving force, the circuit of FIG. 4 becomes aforward or backward direction control. On the other hand, if the motoris connected by way of appropriate gearing to the wheels of the vehicle,a steering action may be achieved.

The circuit of FIG. 4 operates essentially in accordance with thediscussion of FIG. 2 However, an additional transistor switch T6 has itsbase 53 connected to the collector 49 of transistor T5 and its emitter54 connected to positive bias 14. The collector 55 of transistor T6 isconnected to provide positive feedback by way of resistor R7 to the base47 of transistor T5.

When photocell 11 is illuminated, or conversely when photocell 12 isshadowed, transistor T1 and T2 conduct more heavily as hereinbeforedescribed to cause transistor T3 to be driven into saturation. Whentransistor T3 is driven into saturation, a circuit is closed from thecollector of transistor T3 to motor 80 and power source 85. On the otherhand, under the reverse condition of illumination, transistors T4 and T5conduct more heavily, driving transistor T6 into saturation to close thecircuit between transistor T6, motor 80 and source of voltage 86. Whentransistor T3 conducts, connection 82 on the motor is more positive thanconnection 83 so that the motor operates in a first direction. On theother hand, when transistor T6 is saturated, point 82 on the motor ismore negative than point 83 on the motor so that said motor is actuatedin an opposite direction. It may also be understood that a degree ofcontrol is achieved on the state of the motor during the time whentransistors T3 or T6 are rendered conductive, but before they reachsaturation.

Thus, a photocell control circuit responsive to differences in levels ofradiation incident upon a pair of photocell has been described forcontrolling the operative state of a motor located, for example, on atoy vehicle.

I claim:

1. In a toy model of the type which comprises a source of power inseries circuit with a motor, the improvement comprising means responsiveto a difference in radiation between two positions for controlling theoperation of said motor in a predetermined manner, said means including:

a first element responsive to radiation,

' a second element responsive to radiation in circuit with said firstelement, said first element and said second element being connected inseries across said source of power,

amplifier means in circuit with both of said first and second elementsand said motor for actuating said motor in response to a difference inradiation intensity between said first element and said second elementwherein said amplifier means comprises a first transistor having a firstconductivity and including a base, an emitter, and a collector, the baseof said first transistor being in circuit with both said first and saidsecond elements, a second transistor having a conductivity opposite saidfirst conductivity and including a base, an emitter, and a collector,the base of said transistor being in circuit with the collector of saidfirst transistor, and a third transistor having said first conductivityand including a base, an emitter, and a collector, the base of saidthird transistor being in circuit with said collector of said secondtransistor, the collector and emitter of said third transistor being inseries circuit with said source of power and said motor, said thirdtransistor being driven into saturation to actuate said motor throughsaid power source when said first element and said second elementreceive a predetennined difference in radiation intensity, and positivefeedback means in said amplifier means for causing the continuedactuation of said motor afier said difference in radiation between saidfirst element and said second element has ceased wherein said positivefeedback means includes a resistor connected from the collector of saidthird transistor to the base of said second transistor so that saidthird transistor remains in saturation after the difference in radiationbetween the said first element and said second element has ceased. 2.The improvement as defined in claim 1 wherein said first element andsaid second element are each photocells.

3. In a toy model of the type which comprises a source of power inseries circuit with a motor, an electrical circuit adapted to convertsaid toy model into a light responsive toy model, said circuitcomprising:

input means responsive to a difference in radiation between twopositions for controllingthe operation of said motor in a predeterminedmanner, said input means including a first element and a second elementin circuit with said first element, each of said first and said secondelements being responsive to radiation, said first and second elementsbeing electrically connected to said source of power and operative whenradiated so that a difference in radiation intensity between said firstelement and said second element will provide a responsive change in theoutput signal from said input means,

first amplifier means electrically connected to the output of said inputmeans for amplifying the output signal from said input means'under afirst predetermined condition of radiation incident on said first andsecond elements and providing a first amplifier output signal inresponse thereto, second amplifier means electrically connected to theoutput of said input means for amplifying the output signal from saidinput means under a second predetermined condition of radiation incidenton said first and second elements and providing a second amplifieroutput signal in response thereto,

third amplifier means for controlling the actuation of said motorthrough said source of power comprising a transistor, including a base,and a pair of conductive electrodes, said base being in circuit with theoutput of each of said first amplifier means and said second amplifiermeans and capable of being driven into conductive and nonconductivestates in response to a predetermined difference in said radiationintensity between said first and second elements to actuate said motorthrough said source of power when said third amplifier means isconductive, and to deactuate said motor when said third amplifier meansis nonconductive,

positive feedback means in circuit with said third amplifier means andsaid first amplifier means for sustaining the condition of said thirdamplifier means after the dif ference in radiation incident on saidfirst and second elements has ceased, and

output means capable of receiving a signal from one of said conductiveelectrodes of said transistor in said third amplifier means, said outputmeans including means for insulating said motor from said source ofpower when said third amplifier means is nonconductive and connectingsaid motor in circuit with said source of power when said thirdamplifier means is conductive so that the operative state of said motoris controlled by said conductive state of said third amplifier means.

4. An electrical circuit as defined in claim 3 wherein said firstamplifier includes a first transistor and a second transistor being incircuit with output of said input means, and

the base of said second transistor being in circuit with the collectorof said first transistor.

5. An electrical circuit as defined in claim 4 wherein, the base of saidthird transistor is in circuit with the collector of the said secondtransistor.

6. An electrical circuit as defined in claim 5 wherein said positivefeedback means comprises a resistor in circuit between said collector ofsaid third transistor and said base of said second transistor.

7. An electrical circuit as defined in claim 5 wherein said secondamplifier means includes a fourth transistor and a fifth transistor,each comprising a base, an emitter and a collector, the base of saidfourth transistor being in circuit with the output of said input means,and the base of said third transistor being connected to the collectorof said second transistor.

8. An electrical circuit as defined in claim 3 wherein said output meansfurther includes an insulating element in circuit with said source ofpower, said motor and the output of said third amplifier means andarranged so that said insulating element may be bypassed by said thirdamplifier means when said third amplifier means is conductive to actuatesaid electric motor upon receipt of the difference in said source ofradiatron.

9. An electrical circuit as defined in claim 5 wherein said output meansfurther includes an insulating element in circuit with said source ofpower, said motor and the output of said third amplifier means andarranged so that said insulating element may be bypassed by said thirdamplifier means when said third amplifier means is conductive to actuatesaid electric motor upon receipt of the difference in said source ofradiation.

The combination as defined in claim 9 wherein said circuit is furthercharacterized as being capable of attachment to a combination of a toyto provide said combination with remote control capability.

11. The circuit as set forth in claim 3 wherein said first element andsaid second element are each photocells.

12. In a toy model which comprises a source of power electricallyconnected to actuate a motor to propel said model, wherein said sourceof power comprises a first source of electrical potential in seriescircuit with a second source of electrical potential, and wherein saidmotor includes at least a pair of terminals for connection in circuitwith said source of power to actuate said motor, one of said terminalsof said motor being electrically connected to a node common to both ofsaid first and second sources of electrical potential, and wherein themotor is further characterized in that its direction of rotation isresponsive to the direction of current flow therethrough, said toy modelfurther comprising an electrical circuit for controlling flow throughsaid motor comprising:

input means responsive to a difference in radiation between twopositions for controlling the operation of said motor in a predeterminedmanner, said input means including a first element and a second elementin circuit with said first element, each of said first and said secondelements being responsive to radiation, said first and second elementsbeing electrically connected in series with each other and with saidsource of power and operative when radiated so that a difference inradiation intensity between Said first element and said second elementwill provide a responsive change in the output signal from said inputmeans,

first amplifier means electrically connected to the output of said inputmeans for amplifying the output signal from said input means under afirst predetermined condition of radiation incident on said first andsecond elements and providing a first amplifier output signal inresponse thereto,

second amplifier means electrically connected to the output ofsaid inputmeans for amplifyin the output signal from said input means under asecon predetermined condition of radiation incident on said first andsecond elements and providing a second amplifier output signal inresponse thereto,

third amplifier means for controlling the actuation of said motorthrough said source of power comprising a transistor, including a base,and a pair of conductive electrodes, said base being in circuit with theoutput of said first amplifier means and capable of being driven intoconductive and nonconductive states in response to a predetermineddifference in said radiation intensity between said first and secondelements to actuate said motor in a first direction through said firstsource of electrical potential when said third amplifier means isconductive, one of said conductive electrodes of said transistor of saidthird amplifier means being electrically connected to the other terminalof said motor,

fourth amplifier means for controlling the actuation of said motorthrough said source of power comprising a transistor, including a base,and a pair of conductive electrodes, said base being in circuit with theoutput of said second amplifier means and capable of being driven intoconductive and nonconductive states in response to a predetermineddifference in said radiation intensity between said first and secondelements to actuate said motor in a second direction through said secondsource of electrical potential when said fourth amplifier means isconductive,

first positive feedback means in circuit from the output of said thirdamplifier means to the input of said first amplifier means forsustaining the condition of said third amplifier means after thedifference in radiation incident on said first and second elements hasceased,

second positive feedback means in circuit from the output of said fourthamplifier means to the input of said second amplifier means after thedifference in radiation incident on said first and second elements hasceased, and

output means for receiving a signal from said one of said conductiveelectrodes of said transistor in said third amplifier means and saidtransistor in said fourth amplifier means so that the operative state ofsaid motor is controlled by said conductive state of either of saidthird amplifier means and said fourth amplifier means by controlling thedirection of current flow through said motor.

13. The circuit as set forth in claim 12 wherein said first element andsaid second element are each photocells.

14. An electrical circuit as defined in claim 13 wherein each of saidfirst amplifier and said third amplifier includes a first transistor anda second transistor, each of said first and second transistors includinga base, an emitter, and a collector, the base of each of said firsttransistors being in circuit with output of said input means, and thebase of said second transistor being in circuit with the collector ofsaid first transistor in each of said first amplifier and thirdamplifier.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3 ,62l,356D t d November 16 l97l Inventor-(S) Chi-On Kwan It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Page 1, the name of the inventor should read Chi-On Kwan.

Column 1, line 27, "MOreover should read Moreover Column 3, line 70,"0s" should read of Column 4, line 19, "he" should read the and line 56,"wichlike" should read wich-like Column 5, line 11, "Modification"should read Modification Column 7, line 53, insert the direction oftravel of said model by controlling the current before "flow".

Column 8, line 45, insert for sustaining the condition of said fourthamplifier means after "means".

Signed and sealed this 18th day of April 1972.

(SILAL) At best:

EDWARD I-E.FLElCHbJR,JR. ROBERT GOTTSCHALK Attesting OfficerCommissioner of Patents FORM P0-1O5HO-59) USCOMM-DC scam-Pu USvGOVERNMENT PI'UNYING OFFICE I959 0-356-33l

1. In a toy model of the type which comprises a source of power inseries circuit with a motor, the improvement comprising means responsiveto a difference in radiation between two positions for controlling theoperation of said motor in a predetermined manner, said means including:a first element responsive to radiation, a second element responsive toradiation in circuit with said first element, said first element andsaid second element being connected in series across said source ofpower, amplifier means in circuit with both of said first and secondelements and said motor for actuating said motor in response to adifference in radiation intensity between said first element and saidsecond element wherein said amplifier means comprises a first transistorhaving a first conductivity and including a base, an emitter, and acollector, the base of said first transistor being in circuit with bothsaid first and said second elements, a second transistor having aconductivity opposite said first conductivity and including a base, anemitter, and a collector, the base of said transistor being in circuitwith the collector of said first transistor, and a third transistorhaving said first conductivity and including a base, an emitter, and acollector, the base of said third transistor being in circuit with saidcollector of said second transistor, the collector and emitter of saidthird transistor being in series circuit with said source of power andsaid motor, said third transistor being driven into saturation toactuate said motor through said power source when said first element andsaid second element receive a predetermined difference in radiationintensity, and positive feedback means in said amplifier means forcausing the continued actuation of said motor after said difference inradiation between said first element and said second element has ceasedwherein said positive feedback means includes a resistor connected fromthe collector of said third transistor to the base of said secondtransistor so that said third transistor remains in saturation after thedifference in radiation between the said first element and said secondelement has ceased.
 2. The improvement as defined in claim 1 whereinsaid first element and said second element are each photocells.
 3. In atoy model of the type which comprises a source of power in seriescircuit with a motor, an electrical circuit adapted to convert said toymodel into a light responsive toy model, said circuit comprising: inputmeans responsive tO a difference in radiation between two positions forcontrolling the operation of said motor in a predetermined manner, saidinput means including a first element and a second element in circuitwith said first element, each of said first and said second elementsbeing responsive to radiation, said first and second elements beingelectrically connected to said source of power and operative whenradiated so that a difference in radiation intensity between said firstelement and said second element will provide a responsive change in theoutput signal from said input means, first amplifier means electricallyconnected to the output of said input means for amplifying the outputsignal from said input means under a first predetermined condition ofradiation incident on said first and second elements and providing afirst amplifier output signal in response thereto, second amplifiermeans electrically connected to the output of said input means foramplifying the output signal from said input means under a secondpredetermined condition of radiation incident on said first and secondelements and providing a second amplifier output signal in responsethereto, third amplifier means for controlling the actuation of saidmotor through said source of power comprising a transistor, including abase, and a pair of conductive electrodes, said base being in circuitwith the output of each of said first amplifier means and said secondamplifier means and capable of being driven into conductive andnonconductive states in response to a predetermined difference in saidradiation intensity between said first and second elements to actuatesaid motor through said source of power when said third amplifier meansis conductive, and to deactuate said motor when said third amplifiermeans is nonconductive, positive feedback means in circuit with saidthird amplifier means and said first amplifier means for sustaining thecondition of said third amplifier means after the difference inradiation incident on said first and second elements has ceased, andoutput means capable of receiving a signal from one of said conductiveelectrodes of said transistor in said third amplifier means, said outputmeans including means for insulating said motor from said source ofpower when said third amplifier means is nonconductive and connectingsaid motor in circuit with said source of power when said thirdamplifier means is conductive so that the operative state of said motoris controlled by said conductive state of said third amplifier means. 4.An electrical circuit as defined in claim 3 wherein said first amplifierincludes a first transistor and a second transistor, each of said firstand said second transistors including a base, an emitter, and acollector, the base of said first transistor being in circuit withoutput of said input means, and the base of said second transistor beingin circuit with the collector of said first transistor.
 5. An electricalcircuit as defined in claim 4 wherein, the base of said third transistoris in circuit with the collector of the said second transistor.
 6. Anelectrical circuit as defined in claim 5 wherein said positive feedbackmeans comprises a resistor in circuit between said collector of saidthird transistor and said base of said second transistor.
 7. Anelectrical circuit as defined in claim 5 wherein said second amplifiermeans includes a fourth transistor and a fifth transistor, eachcomprising a base, an emitter and a collector, the base of said fourthtransistor being in circuit with the output of said input means, and thebase of said third transistor being connected to the collector of saidsecond transistor.
 8. An electrical circuit as defined in claim 3wherein said output means further includes an insulating element incircuit with said source of power, said motor and the output of saidthird amplifier means and arranged so that said insulating element maybe bypassed by said third amplifier means when said Third amplifiermeans is conductive to actuate said electric motor upon receipt of thedifference in said source of radiation.
 9. An electrical circuit asdefined in claim 5 wherein said output means further includes aninsulating element in circuit with said source of power, said motor andthe output of said third amplifier means and arranged so that saidinsulating element may be bypassed by said third amplifier means whensaid third amplifier means is conductive to actuate said electric motorupon receipt of the difference in said source of radiation. 10 Thecombination as defined in claim 9 wherein said circuit is furthercharacterized as being capable of attachment to a combination of a toyto provide said combination with remote control capability.
 11. Thecircuit as set forth in claim 3 wherein said first element and saidsecond element are each photocells.
 12. In a toy model which comprises asource of power electrically connected to actuate a motor to propel saidmodel, wherein said source of power comprises a first source ofelectrical potential in series circuit with a second source ofelectrical potential, and wherein said motor includes at least a pair ofterminals for connection in circuit with said source of power to actuatesaid motor, one of said terminals of said motor being electricallyconnected to a node common to both of said first and second sources ofelectrical potential, and wherein the motor is further characterized inthat its direction of rotation is responsive to the direction of currentflow therethrough, said toy model further comprising an electricalcircuit for controlling flow through said motor comprising: input meansresponsive to a difference in radiation between two positions forcontrolling the operation of said motor in a predetermined manner, saidinput means including a first element and a second element in circuitwith said first element, each of said first and said second elementsbeing responsive to radiation, said first and second elements beingelectrically connected in series with each other and with said source ofpower and operative when radiated so that a difference in radiationintensity between said first element and said second element willprovide a responsive change in the output signal from said input means,first amplifier means electrically connected to the output of said inputmeans for amplifying the output signal from said input means under afirst predetermined condition of radiation incident on said first andsecond elements and providing a first amplifier output signal inresponse thereto, second amplifier means electrically connected to theoutput of said input means for amplifying the output signal from saidinput means under a second predetermined condition of radiation incidenton said first and second elements and providing a second amplifieroutput signal in response thereto, third amplifier means for controllingthe actuation of said motor through said source of power comprising atransistor, including a base, and a pair of conductive electrodes, saidbase being in circuit with the output of said first amplifier means andcapable of being driven into conductive and nonconductive states inresponse to a predetermined difference in said radiation intensitybetween said first and second elements to actuate said motor in a firstdirection through said first source of electrical potential when saidthird amplifier means is conductive, one of said conductive electrodesof said transistor of said third amplifier means being electricallyconnected to the other terminal of said motor, fourth amplifier meansfor controlling the actuation of said motor through said source of powercomprising a transistor, including a base, and a pair of conductiveelectrodes, said base being in circuit with the output of said secondamplifier means and capable of being driven into conductive andnonconductive states in response to a predetermined difference in saidradiation intensity between sAid first and second elements to actuatesaid motor in a second direction through said second source ofelectrical potential when said fourth amplifier means is conductive,first positive feedback means in circuit from the output of said thirdamplifier means to the input of said first amplifier means forsustaining the condition of said third amplifier means after thedifference in radiation incident on said first and second elements hasceased, second positive feedback means in circuit from the output ofsaid fourth amplifier means to the input of said second amplifier meansafter the difference in radiation incident on said first and secondelements has ceased, and output means for receiving a signal from saidone of said conductive electrodes of said transistor in said thirdamplifier means and said transistor in said fourth amplifier means sothat the operative state of said motor is controlled by said conductivestate of either of said third amplifier means and said fourth amplifiermeans by controlling the direction of current flow through said motor.13. The circuit as set forth in claim 12 wherein said first element andsaid second element are each photocells.
 14. An electrical circuit asdefined in claim 13 wherein each of said first amplifier and said thirdamplifier includes a first transistor and a second transistor, each ofsaid first and second transistors including a base, an emitter, and acollector, the base of each of said first transistors being in circuitwith output of said input means, and the base of said second transistorbeing in circuit with the collector of said first transistor in each ofsaid first amplifier and third amplifier.